In recent years, a vehicle such as an automobile is increasingly equipped with an electronic key as standard. Without even the need of pressing a button for locking or unlocking like a remote controller, this electronic key enables a user to unlock a door lock by just approaching the vehicle or touching a door knob, or start an engine by just pressing a start button without inserting a key thereinto upon getting into the vehicle.
In Patent Document 1, for example, the electronic key are used in a rent-a-car system. In this technique, when a rental contract is established, an electronic key is sent from a center to a portable terminal, and becomes valid at a reserved time, which allows a rental car to be locked, unlocked, or the engine to be started.
In addition, in Patent Document 2, for example, there is disclosed a technique in which functions available to a user using a car sharing service are transmitted to a mobile device in a limited state at the time of reservation. This technique discloses the one that selects what in which function (for example, in, charging based on an available option such as navigation and ETC) is used among the functions provided in the rental car, which provides a function limitation only at the time of reservation.